Pitch stabilization system for water going vessels



Nov. 15, 1966 s. B. FIELD ETAL 3,285,216

PITCH STABILIZATION SYSTEM FOR WATER GOING VESSELS Filed Sept. 22, 19645 Sheets-Sheet 1 INVENTORS Sheldon 15. Fzla 772 omas 5 Br Edges BYMarti/2 FZeiz m www ATTORNEYJ' Nov. 15, 1966 5,5, FIELD ETAL PITCHSTABILIZATION SYSTEM FOR WATER GOING VESSELS Filed Sept. 22, 1964 5Sheets-Sheet 2 INVENTORS d 5 am in t A F m 5 d H %m a 57M Nov. 15, 19665,5. ET AL PITCH STABILIZATION SYSTEM FOR WATER GOING VESSELS 5Sheets-Sheet 5 Filed Sept. 22, 1964 INVENTORS Shela/0n 6. Field Thomas EBridges Marti/2 Fleit Mw M ATTORN Y) United States Patent 3,285,216PITCH STABILIZATION SYSTEM FOR WATER GOING VESSELS Sheldon B. Field,Floral Park, and Thomas F. Bridges, Port Washington, N.Y., and MartinFleit, Falls Church, Va., assignors to John J. McMullen Associates,Inc.,

New York, N.Y., a corporation of New York Filed Sept. 22, 1964, Ser. No.398,220

7 Claims. (Cl. 114-122) This invention relates to a system forstabilizing a water going vessel in the pitch plane and moreparticularly a pitch stabilization system which controls a flow ofliquid through portions of the ship for the purpose of imparting pitchstabilizing forces to the ship.

With the increased ocean and water travel, both pleasure and merchant,there has arisen a great need for ship stabilization in the pitchingplane of the vessel. In the case of pleasure cruises, pitchstabilization is desirable to make the ocean voyage more pleasant andattractive to the passengers for the purpose of improving their comfortand well-being. Pitch stabilization is important for merchant vessels sothat ship speed need not be varied and other measures taken duringvoyage to avoid extreme pitching. Furthermore, great pitching may resultin injury or loss to cargo.

Great strides have been made in the roll stabilization art using passivestabilizers, and these stabilizers are generally characterized by anelongated container and a body of fluid therein moving from one side ofthe container to the other in response to the roll of the ship, so thata stabilizing moment is imparted to the ship in opposition to the rollthereof. See, for example, US. Patent No. 3,054,373, US. Patent No.3,083,672, and US. Patent No. 3,083,674.

However, the problems encountered in stabilizing the vessel in thepitching plane are greatly different from those of stabilizing thevessel in the roll plane. Due to the large longitudinal metacentricheight of the vessel and the large exciting pitching moment imparted bythe waves to the vessel, it would be impractical, if not impossible, tohave a movement of fluid through the longitudinal axis of the ship whichimparted any significant stabilizing moment to the ship in the pitchingplane. This impracticality is enhanced by the fact that the period ofpitching is relatively short in relation to the length of the vessel, sothat there would have to be great volumes of liquid moved through greatdistances within the ship to impart any appreciable pitch stabilizingmoment to the ship. Furthermore, any ducting or channel means locatedthroughout the longitudinal dimension of the vessel would take far toomuch space from the designed cargo handling capabilities of the vessel.

Another problem encountered in pitch stabilizing a vessel stems from thegenerally accepted fact that the vessel will reach its most extremevalue when the period encountered by the waves in equal to the naturalperiod of pitching of the vessel and when the length of the wave is thesame as the length of the ship.

The present invention solves the above problems without the disadvantageof having great channels or ducting networks existing throughout thevessel. Stated briefly, the present invention incorporates channels ortanks located at the bow and/or stern of the vessel and enables water toenter and leave the bow and/ or stem in a controlled manner such thatthe weight of the water or the movement of the water through and bowand/or stern portion of the vessel will impart stabilizing forces at thebow and stem of the vessel. It can be understood that these forcesimparted at the bow and/or stern of the "ice vessel take advantage ofthe long pitching stabilization moment arm for the vessel.

Therefore, it is an object of the present invention to provide astabilization system which stabilizes the ship in the pitching plane.

It is another object of the present invention to provide a pitchingstabilization system which imparts forces at the bow of the ship inresponse to the upward or downward movement of the bow, said forcesopposing the upward or downward movement of the bow.

It is another object of the present invention to provide a pitchstabilization system comprising two subsystems, one at the bow and oneat the stern of the ship.

Other and further objects of the present invention will become apparentwith the following detailed description when taken in view of theappended drawings in which:

FIG. 1 is a side elevation of the vessel showing the stabilizationsystem in the bow thereof;

FIG. 2 is an exploded top plan view taken in section along line 22 ofFIG. 1;

FIG. 3 is a front elevation showing the disposition of the bowstabilization system;

FIG. 4 is a side elevation of another embodiment of the invention; and

FIG. 5 is a top plan view taken in section along line 55 of FIG. 4.

Referring to FIGS. l3 in detail, there is shown a ship generallyindicated as 10 having a how section 12. Mounted in the bow section 12is the pitch stabilization system 16 having an inlet port 18 at or nearthe extreme front end of the ship and a pair of outlet ports 20 mountedon either side of the vessel. A pair of overhead pipes 22 communicatewith the inlet port 18 and outlet ports 20 and define a tortuous pathand have an elbow 22a which is substantially higher than the inlet port18. In a like manner, another pair of pipes 24 located below theoverhead pipes 22 also communicate with inlet port 18 and outlet ports20. Pipes 24 also define a tortuous path and have an elbow 240 which issubstantially lower than inlet port 18. A flapper or valve 26 is hingedin the region of the inlet port 18 for selectively opening and closingthe respective paths tor pipes 22 and pipes 24. Conventional manual orautomatic operating means 28 is mechanically linked to valve flapper 26to control the opening and closing of the respective paths in responseto the pitching of the ship.

A sliding valve or V-shaped plate 21 is slidably secured to the frontpart of how 12 by guide members 23. The valve plate 21 is secured in itsupper position by conventional latching means (not shown) when the pitchstabilization system is in use. When it is desired not to use the pitchstabilization system, the valve plate 21 is placed in its lowermostposition and secured thereto by horizontal limiting guides 25. With thevalve plate 21 in its closed position, that is the lowermost position,the pitch stabilization system does not function and the hydrodynamicdesign of the bow section is not diminished.

The operation of the system disclosed in FIGS. l3 will now be described.It can be seen that inlet port 18 is located well below the water lineas the vessel rides in the sea. As ship 10 is propelled forward, thereis a great rush of water in throught port 18, through one of the sets ofpipes 22 or 24, and out through the port 20. When ship 10 is in apitching condition and the bow of the ship is substantially above thestern so that the bow will begin moving downward and the stern upwardabout the pitching axis, control means 28 will force valve 26 to thelower position (FIG. 1) so that great volumes of water rush throughinlet port 18 up through the overhead pipes 22 and out through ports 20.As the great volumes of water flow around the elbows 22a, the kineticenergy thereof imparts an upward force to the 'bow of the ship inopposition to the downward motion of the bow of the 'ship so thatstabilization is imparted thereto with substantially the maximum momentarm possible. When the bow of the ship is in its lowermost position andstarts to rise, control means 28 throws valve 26 to its upper positionso that great volumes of water rush through port 18 into the lower pipes24 and outlet ports 20. As the direction of this great volume of movingfluid is changed due to elbow 24a, a downward force is imparted to thebow of the ship in opposition to the rising thereof. In this way, it canbe seen that pitching stabilization forces are imparted to the bow ofthe ship in opposition to the pitch motion thereof.

When calm seas are encountered and the pitch stabilization system is notto be used, V-shaped valve plate 21 is lowered to close olf the inletport 18.

It is pointed out that the ship need not be under way for the system tofunction. The upward and downward movement of the bow is suflicient tocause water to pass through port 18, pipes 22 and 24, and ports 20.However, the system will operate more efficiently When the vessel ismoving forward.

Referring now to the embodiment shown in FIG. 4 of the drawings, thereis illustrated a pitch stabilization system for ship which comprises twosubsystems, that is the bow subsystem 32 and the stern subsystem 34. Thebow subsystem comprises a valve inlet port 36 which is normally openwhen the subsystem is in operation and a pair of outlet ports 38 mountedon the bottom and opposite sides of the vessel. Inlet opening 36communicates with an enlarged tank 40, said tank 40 having a pair ofopenings 42 located at the substantially bottom end of said tank 40. Apair of pipes 44 are disposed in free communication with tank outlet 42and outlet ports 38. The incorporation of pipes 44- is the preferredembodiment; however, if desired, the outlet ports 38 can be disposed inthe common wall of the bow of the ship and tank 32. This arrangementwould avoid the necessity of using connecting pipes 44.

The top of tank 40 is open to the atmosphere or communicates with theatmosphere by the use of any known means such as piping or venting 45.It will be noted that inlet port 36 is located substantially at thewater line of the vessel, and that tank outlet 42 and outlet port 38 arelocated substantially below the water line.

The stern subsystem 34 comprises a similar tank 46 and a pair of outletports 48 which provide communication between tank 46 and the ambient.The midsection of tank 46 is preferably disposed below the water linesimilar to tank32. Port 48 is normally valved open when the system is inoperation. A pair of inlet ports 50 defined on either side of the shipcommunicate with tank 46 via a pair of pipes 52 and tank inlets 54. Itcan be seen that the inlet ports 50 are located substantially at theWater line of the vessel and the outlet port 48 is located substantiallynear the bottom of tank 46.

Tank 46 is venter to the atmosphere through pipe 47.

The operation of the system in FIG. 4 will now be described. Let it beassumed that the vessel-10 is moving in a forward direction and isencountering the normal degree and frequency of pitching. As the bownoses deeper into the water and the stern rises, there will be asubstantial amount of liquid flowing through the inlet port 36 into tank40 and since the flow of liquid into tank 40 is greater than the flow ofliquid out of tank 40 through outlet ports 38, there will be a netincrease in the amount of liquid within tank 40. Therefore, as the bowreaches its lowermost position and begins to rise, there will be agreater weight of liquid within tank 40, thus opposing the rising -ofthe bow of the ship 10'. As the vessel passes through a horizontalposition, inlet port 36 will rise above the water line so that water nolonger flows into tank 40. As the bow of the ship continues to rise,

4 the level of liquid within the tank 40 is substantially above thewater line so that there is an increased potential pressure head givento the liquid within tank 40, and consequently, a great amount of liquidwill pass through pipes 44- and outlet ports 38. Therefore, the weightin the bow of the ship is reduced as the bow of the ship rises to itsmaximum height so that the lowering of the 'bow is not aided byincreased weight therein. As the bow again noses down past the waterline, there is increased buoyancy in tank 40 due to the lower liquidlevel in said tank. Said increased buoyancy exists but is continuallydecreased as water rushes through inlet port 36 to again fill the tank32. The water rushing through inlet port 36 during this portion of thepitching cycle fills tank 32 to the height which opposes the rising ofthe bow as aforementioned. In this way, the pitch stabilization forcesare imparted to the bow of the ship with the substantially maximumpitching moment arm.

The stern pitch stabilization subsystem operates in a similar manner,that is when the stern of the ship is below horizontal, the inlet ports50 are below the water line so that tank 46 takes on a great volume ofwater and the level of liquid therein rises. As the stern of the shipbegins to rise, the greater weight of water in tank 46 opposes saidrising of the stern and imparts a downward force thereto. As the sternof the ship passes through the horizontal'position and continues torise, tank 46 ceases to take water because the inlet ports 50 are abovethe water line. At this time, the increased level of water within tank46 is given a greater potential pressure head so that outward flow ofwater through outlet port 48 continues at a greater rate so that theinevitable downward movement of the stern will not be aided. As thestern plunges into the water past the horizont-al position, there is anincreased buoyancy aiforded by tank 46 until the liquid level withinsaid tank coincides with the water line.

It should be understood that either the bow or stern subsystem can workindependently of each other; and, if desired, one or the other subsystemcan be omitted from the design of the vessel.

Again, it should be remembered that ports 36, 48 and 50 are valve openedand remain open as long as stabilization is to be imparted to the ship.If the systems are no longer needed, the respective valves are closed byconventional means (not shown) so that pitching is not in duced invessel 10. Port 36 is closed in a manner as described above. It can alsobe seen that the ship need not be under way for the subsystems to beeffective.

It can be seen that the present invention can be used to impart aconstant force at the bow or stern of the ship to compensate for acondition which causes the ship to ride at some angle with respect tothe horizontal. For example, if the stern of the ship were damaged sothat the stern took on great quantities of water and lowered the sternof the vessel, tank 32 located at the bow of the ship could be entirelyfilled with water so that the attitude of the vessel would be broughtmore nearly to the horizontal. Furthermore, as another example, if itwere necessary to unevenly distribute the cargo of the vessel such thatthe bow of the ship is lower than the stern, the water from tank 32 canbe removed and ports 36 and 38 sealed off so that the bow of the shipwould have increased buoyancy and, thus again, the tank corrects theattitude of the vessel to be more near the horizontal.

It should be understood that the present disclosure is of preferredembodiments and the invention should not be limited to the detailedillustrated structure. For example, the number and exact locations ofthe bow and stern tanks can be varied, the number of the ingress portsand outlet ports can be varied, and the number and locations of thepipes shown in the system of FIGS. 1-3 can be varied Without departingfrom the spirit of the invention.

What is claimed is:

1. A pitch stabilization system for a water oing vessel comprisingliquid containing means mounted in one end of the vessel for impartingpitch stabilizing forces to the vessel in response to the fluid flowingtherethrough, inlet means disposed at one end of said liquid containingmeans for enabling liquid to flow into said liquid containing means, andoutlet means communicating with said liquid containing means forenabling liquid to flow out from said liquid containing means, saidliquid containing means comprising at least a pair of pipes, each havingan elbow, one of said pipes having an elbow disposed above said inletmeans and the other of said pipes having an elbow disposed below saidinlet means, and each of said pipes communicating with said inlet meansand said outlet means.

2. A pitch stabilization system as set forth in claim 1, furthercomprising valve means for selectively and alternatively directingliquid that enters said inlet means through one and then the other ofsaid pipes, and means for controlling the position of said valve means.

3. A pitch stabilization system for water going vessels comprising atleast one first opening located substantially at one end of the vessel,at least one second opening defined in the sides of the vessel, andmeans mounted within the vessel for enabling fluid to pass through saidfirst and second openings through a portion of the vessel, said firstopening being located substantially at the front of the bow section ofthe vessel, said stabilization system further comprising a movable valveplate having a profile substantially the same as the profile of the bowof the vessel slidably mounted to the bow of said vessel, said platebeing adapted to selectively open and close the communication betweensaid first opening and the ambient.

4. A pitch stabilization system for water going vessels comprising atank mounted at one end of the bow and stern sections of the vessel,inlet means extending through said vessel to enable the liquid ambientto enter the tank, said inlet means positioned vertically near theexpected calm waterline and said tank having a large capacity below saidinlet means so that water entering the tank through said inlet meansneed not overcome the static pressure head of the major portion of thewater already in the tank, and outlet means for establishingcommunication from said tank to the liquid ambient at a verticalposition well below said inlet means.

5. A pitch stabilization system as set forth in claim 4 wherein saidinlet means is positioned near the forward side of the tank and thestabilization system further comprises means for equalizing the airpressure in the tank so that water can freely enter and leave the same.

6. A pitch stabilization system as set forth in claim 5 wherein saidinlet means comprises a pair of inlets each arranged on opposite sidesof the vessel and each inlet communicating with the tank.

7. A pitch stabilization system for a water going vessel, comprising astern subsystem located in the stern of the vessel and a bow subsystemlocated in the bow of the vessel, said stern subsystem comprising atank, inlet means defined on at least one side of the vessel andcommunicating with said tank said inlet means positioned vertically nearthe expected calm waterline of the vessel, and outlet means defined nearthe rear of the vessel and communicating with said tank, said outletmeans being disposed well below said inlet means, said bow subsystemcomprising a bow tank, second inlet means communicating with said bowtank, said second inlet means positioned vertically near the expectedcalm waterline for the vessel, second outlet means defined on at leastone side of the vessel and communicating with said tank, and said second outlet means being disposed well below said second inlet means.

References Cited by the Examiner UNITED STATES PATENTS 1,444,150 2/1923Gadomski 114-125 2,098,531 11/1937 Baze 114122 3,155,065 11/1964Strumskis 114-122 FOREIGN PATENTS 451,995 8/ 1936 Great Britain.

MILTON BUCHLER, Primary Examiner.

FERGUS S. MIDDLETON, Examiner.

T. M. BLIX, Assistant Examiner.

4. A PITCH STABILIZATION SYSTEM FOR WATER GOING VESSELS COMPRISING ATANK MOUNTED ON ONE END OF THE BOW AND STERN SECTIONS OF THE VESSEL,INLET MEANS EXTENDING THROUGH SAID VESSEL TO ENABLE THE LIQUID AMBIENTTO ENTER THE TANK, SAID INLET MEANS POSITIONED VERTICALLY NEAR THEEXPECTED CALM WATERLINE AND SAID TANK HAVING A LARGE CAPACITY BELOW SAIDINLET MEANS SO THAT WATER ENTERING THE TANK THROUGH SAID INLET MEANSNEED NOT OVERCOME THE STATIC PRESSURE HEAD OF THE MAJOR PORTION OF THEWATER ALREADY IN THE TANK, AND OUTLET MEANS FOR ESTABLISHINGCOMMUNICATION FROM SAID TANK TO THE LIQUID AMBIENT AT A VERTICALPOSITION WELL BELOW SAID INLET MEANS.